Compressor



Aug. 11, 1959 Filed Dec. 3, 1954 R. E. sYKEs 2,899,130

COMPRESSOR 5 Sheets-Sheet l Aug. 11, 1959 R. E. SYKES COMPRESSOR Filed Dec. 3, 1954 3 Sheets-Sheet 2 I 151 221 7 fioerf 5 59/7125.

R. E SYKES Aug. 11, 1959 COMPRESSOR 3 Sheets-Sheet 3 Filed Dec. 3, 1954 United States Patent Ofiice 2,899,130 Patented Aug. 11, 1959 COMPRESSOR Robert E. Sykes, Evanston, Ill., assignor to Bell & Gossett Company, Morton Grove, 111., a corporation of Illi- Application December. 3, :1954, Serial No. #172,987

'8 Claims. "(CL 230- 182) 'case and tiHtO the 'bell housing :at V the .end .of the -motor.

A further iobject' is I01 deviseua compressor of the character :indicated wherein the :crank case includes a chamhers-that defines and istin'rheat exchangerelation to'the coolingair passageithrough the:crank :case and in which 'such chamber serves as an aftercooler :for .a single -or twin piston "single stage compressor, or. as an intercooler for aitwostageicompressor.

A further object is to provide a crankzcase-for'aicompressor as indicated 'which;is constructedandarranged so that the cylinder or cylinders with their associated zhead or heads may beslipped over the associated piston or ,pistons after the-latter have been assembled to the eccentric shaftand beforefthe'crank'caseis fastened .to the cylinder head or heads.

A furtherobject is the provision-of'acompressoras above set forthhaving twin, 'equisized openings in the cylinder head-thereof, one opening receiving in'super- .2 Fig; 2- is a sectionalong the-line 22 in Fig. -1. *Fig. 3 is a slightly enlarged, detail section along the -Fig. 4-is'an elevation of-the compressor crank case as viewed in the direction of-the-arrow 4 in Fig. '2.

By way of example and not of limitation,-the invention will bedescribedas appliedtoatwo stage aircompressor of 'relatively small size, ie, one capable I of being-driven by 2: to horsepower, electric motors, but it willbe-apparent that features thereof are applicabletosingle and twin piston'compressors as well as generally to compres- -sors of any size, or multiplicityio'f cylinders.

Referring to'=Figs. i1 and 2, the numeral 10 designates a base-member which is preferably arcuateshaped on'its upper sideto receive the cylindrical'housing of an electric motor 11 and an axially aligned, cylindrical crank -case 12. Fheend of'the'motor drive shaft 13 is received within and is-drivably'connected-to the adjacent socketed en'd of a -fan shaft 14 which is supported bythe motor shaft 13, the fan shaft 14 being coaxial with the motor l l and-crank case d2and having attached to its opposite end a fan 15. 'The motor s'haft 13 is-secured by'a key 16 to juxtaposed eccentrics -'17 and 1 8 which drivably connect through 'connecting rods 19 and 20 with a low-pressure piston zl and a guide -pi'ston' 22, all respectively, each pistonjbeing of'the trunk type.

In :the arrangement shown, the piston "21 constitutes a part of the low-pressure side of thecompressor and it --reciprocates within a s'leeve cylinder 23 whose innerend -is=exposed-within the crank-case '12 and whose outer end is annularly roughened=orcorrugated at 24 to facilitate the casting therearoundand locking connection therewith sofa cylinder *head 25. Preferably, the head 25 'is composed "of a metal 'havinga relatively high thermalcoefficie-nt of conductivity, such 'aszalurriinum, while thecylinder 23 is composed of a metal having'a relatively'low thermal'coeflicient of conductivity-an'd good wearing qualities, suchas-castiron. The head "25 is suitably -bo'lted to the crank case 1-2 which may also be-formedof'alunii- :imposed relation a filter assembly and a :fiapper, inlet valve assembly, andithe otheropening receivingiin like relation a relief valveassembly and a flapper, exhaust valve assembly, thus :enabling rpositioningof these pairs of assemblies ineither opening.

A further objectis'todevice'a two stage compressor of the positive displacementtype in which'the guiding portion of the high=pressure piston :has the same :diameter as'the low pressure-piston and:in which the high pressure guiding portionis arranged-to directa cooling flow of-air around the high pressure cylinder and-connectingrod bearing.

These and :further objects-of the invention'will be set vforth in the following specification, reference being had to the accompanying drawings, .and the novel means by which the objects areefiectuated will be definitely pointed out in the claims.

In the drawings:

Fig. 1 is a side. elevation of "the compressor, partlyin section.

num and has full metal to metal contact therewith to ifacilitateLheat transmission for a purpose presently-ex- .plained,-eXcept-in the regionofan exhaustpassage as .presently described.

Extending throughithe head'25 are equisizedytapped holes .26 and 27 whoseinnerends communicate with a low compression chamber '28 between the head and piston 21. In the outer portion of the-hole -26 is mounted .a conventional filter assembly 29iforfiltering air flowing therethroughand:inthe innerportion of the same hole 50 isithreaded a conventional flapper, inlet valve designated generally by the numeral 30 :and which .preferablyin- .cludes .33. wrench receiving socket 31 oniits inlet side'to facilitate mounting.andremovalthereof. It willbe ap- :parent that, during the suction stroke of the piston 21, theflapper elementof the=inlet valve 30 will open-to ad- ;mita charge. of air tothe compression chamber =28.and

will close dnringthercornpression stroke ofthe piston;21.

.-In the inner part of the hole 27 is threadeda conventional flapper, exhaust valve 32 which also preferably includes a wrench socket 33 on the exhaust side thereof for the same purpose as noted for the inlet valve 30, While in the outer part of the-hole 27 is threadeda conventional relief valve 34 of the spring loaded ball type which is adjusted to open at a, predetermined safetypressure which-is higher than thenormal operating pressure ofthe low pressure side of'the compressor. The flapper element of .the .exhaustvalve 32 functions in the well known manner at a proper point in the compression stroke of the piston 21 to discharge compressed air into a space between the opposed ends of the exhaust and relief valves 32 and 34, respectively.

The space 35 communicates through passages 36 and 37 in the cylinder head 25 and crank case 12, respectively, with a chamber 38 which is parti-annular in shape and extends axially for a major portion of the length of the crank case 12 (see Fig. 1). The mating ends of the passages 36 and 37 are sealed by a gasket 39 which is of such minor area compared to the otherwise metal to metal contact between the crank case 12 and head 25 as not to exercise any substantial restraint on heat transmission therebetween.

The chamber 38 is closed at one end and open at the opposite or left end as viewed in Figs. 1 and 2 in registration with the adjacent part of an annular chamber 40 provided in that face of a ring member 41 which .abuts and is appropriately secured to the adjacent end of and functionally is a part of the crank case 12. Secured to the other face of the ring member 41 is a suitably apertured grill 42 through which air is drawn by the fan 15 to fiow through the member 41 and crank case 12 for discharge through a perforated, ventilating band 43 which is located between the adjacent ends of the motor 11 and crank case -12, respectively. The inner surface of the ring member 41 is provided with a plurality of radially inward and circumferentially spaced ribs 44 which are in heat exchange relation to air in the annular chamber 40. These ribs extend to the periphery of the member 41 in abutting relation to the grill 42 so that the fan air also flows radially outward between the ribs 44 and externally over the crank case 12. Preferably, the ring member 41 is composed of a material having a high thermal conductivity, such as aluminum.

The low pressure air discharged into the annular chamber 40 passes into another parti-annular chamber 45 which is generally oppositely disposed to the chamber 38, the chambers 38, 40 and 45 together constituting a pulsation chamber. From the chamber 45, the air flows successively through passages 46, 47 and 48 provided, respectively, in the crank case 12, the annularly flanged portion 49 of a sleeve guide cylinder 50 and a cylinder head 51. Gaskets 52 and 53 having a size comparable to the gasket 39 are interposed between the ends of the passages 46 and 47, and 47 and 48, respectively. The guide cylinder 50 through its flanged portion 49 otherwise has metal to metal contact with the crank case 12 and cylinder head 51. The cylinder head 51 is preferably composed of a good thermally conductive material, such as aluminum, and is cast around and in locking connection with the corrugated, annularly flanged end 54 of the high pressure cylinder 55 whose bore is less than that of the low pressure cylinder 23 and which is formed of material like the latter cylinder.

Reciprocable within the high pressure cylinder 55, which is generally opposite to but slightly olfset from the low pressure cylinder 23, is a high pressure piston 56 which is preferably integral with or may be otherwise connected to the guide piston 22 that has the same diameter as the low pressure piston 21. Extending radially from the skirt 57 of the cylinder 55 and in heat exchange relation therewith is a plurality of circumferentially spaced ribs 58 (see Figs. 2 and 3) which extend into an annular space 59 included between the guide and high pressure cylinders 50 and 55, and the guide and high pressure pistons 22 and 56, all respectively. The space 59 is closed at one end by the flanged end 54 and communicates at the opposite end through a plurality of ports 60 with the interiors of the guide and high pressure pistons 22 and 56 so that as the composite piston reciprocates, designated generally by the numeral 61 and including the guide and high pressure portions thereof, air flows into and out of the space 59 with a cooling effect on the high pressure cylinder 55 and the bearing of the connecting rod 20. Also, as shown in Fig. 2, the inner end of the guide cylinder 50 extends within the crank case 12 and the interiors of the high pressure and guide pistons 56 and 22, respectively, are subjected to the cooling effect of the fan air flowing through the crank case 12.

The head 51 is tapped to provide a pair of holes 62 and 63 which are sized the same as the holes 26 and 27 and extend therethrough with their inner ends communicating with the high compression chamber 62. In the inner end of the hole 62 is located a flapper, inlet valve 64 similar to and which may be of the same size as the inlet valve 30. The inlet side of the valve 64 is spaced from a plug 65 that closes the outer end of the passage 62 to define a chamber that constantly communicates with the delivery end of the passage 48.

In the inner end of the hole 63 is positioned a flapper, exhaust valve 67 and spaced therefrom in the same hole is a flanged plug 68 having a cavity 69 communicating with the discharge side of the exhaust valve 67. The flange of the plug 68 sealingly grips a pair of oppositely disposed, thick washers 70 against the cylinder head 51 and in one of these washers is mounted a fitting 71 providing communication between a conventional aftercooler 72 and a port 73 in the plug 68 which connects with the cavity 69. Also mounted in the plug 68 and providing communication between the atmosphere and cavity 69 is a relief valve 74 similar to the valve 34 but adjusted to a higher pressure. The valves 64 and 67 may also include wrench sockets 75 and 76, respectively, in their outer portions to facilitate their insertion and removal.

In operation, air is drawn into the low compression chamber 28, compressed to a determined value and discharged into the chambers 38, 40 and 45 and from the latter, the low pressure air is drawn into the high compression chamber 62, compressed to a higher value, and discharged to the aftercooler 72. During this process, the chambers 38, 40 and 45 together act as an intercooler due to the heat withdrawing action of the air flowing over the ribs 44 and the interior surface of the crank case 12 and through these ribs and over the exterior surface of the crank case. Moisture condensed in such chambers may be evacuated at intervals through a suitable drain (not shown), but preferably located along the line A--A in Fig. 2.

The air cooling action is also effective over the eccentric bearings, the adjacent end of the motor housing, around the low pressure and guide cylinders 23 and 50, respectively, which as shown in Fig. 2 have substantial portions of their exteriors spaced from the crank case 12, and interiorly of the low pressure piston 21 and the composite piston 61. This construction insures cool operation of the compressor and long life of the parts.

Cooling is further facilitated by the heat transmitting connection arising from the metal to metal contact between the low pressure head 25 and the crank case 12 and low pressure cylinder 23, respectively, and between the crank case 12, guide cylinder flange 49, high pressure head 51 and high pressure cylinder 55 where these parts are severally in contact as shown in Fig. 2.

The equisizing of the threaded holes in the low and high pressure cylinder heads 25 and 51, respectively, provides certain inventory advantages with respect to the threaded bodies of the several valve and filter assemblies. Moreover, these assemblies may be inserted and removed without disturbing the associated passage or hose connections.

In the two stage arrangement as shown, the construction of the composite piston 61 with its connection between the high pressure piston 56 and guide piston 22 which has the same diameter as the low pressure piston 21 results in a reduction in the stresses and bearing pressures in the composite piston, as well as a utilization of the same SiZc P n pin and connecting rod as for the low pressure piston, 2.1.

- 7 This compressor is characterized by-a certain versatility \of application with respect to the utilization of-its basic eomp'onents. For example, the compressor as-shownin Fig. 2 .can .be changed to one of thesingle piston type .mere1y-by removing all of the parts associated-with the "high pressure side and attaching a non-perforated, dummy head (not shown) to the crank case 12 to close the opening therein in what had been the high pressure location. In such a case, the pulsation chamber including the chambers 38, 40 and 45 serves as an aftercooler for air discharged from the compression chamber 28 and this air may be led from the pulsation chamber at any convenient point thereof.

Further, the compressor may be simply modified to one of the twin piston single stage type merely by substituting for the high pressure assembly shown in Fig. 2 a duplicate of the low pressure assembly shown in the same figure. Both of the pistons then discharge into the pulsation chamber which also serves as an aftercooler due to the cooling action of the fan air. Air would be tapped from this chamber in the same manner as indicated for single piston operation.

Another feature of the invention resides in the arrangement of the crank case 12 (see Fig. 4) which is bifurcated from the motor end thereof and along a transverse diameter to provide generally oppositely related, U-shaped pockets 77 and 78 which are slightly displaced axially from each other. In the two stage design shown in Fig. 2, the low pressure assembly is received within and extends through the pocket 77, while the high pressure assembly occupies a similar relation to the pocket 78.

This crank case construction materially simplifies and reduces the cost of assembly. For each pressure side, the piston'connecting rod sub-assembly is mounted on the motor shaft 13 and the associated cylinder with its accompanying parts is slipped over the cooperating piston before the crank case 12 is slipped axially to receive the low and high pressure assemblies in the pockets 77 and 78, respectively.

All of the foregoing attributes are reflected in a highly efiicient compressor having marked cooling qualities, versatility of application while retaining basic components, and which is characterized by certain production advantages.

I claim:

1. In a compressor, in combination: casing means forming a compressor body having the general shape of an annulus to provide an axial air space, said body including radially spaced inner and outer exterior peripheral walls defining a pulsation chamber that is isolated from and extends about the periphery of said space, said body having a pocket opening radially therethrough, a fluidcompression assembly in said pocket and including a cylinder and head therefor carried by said body, a piston reciprocable in the cylinder, and means in said space for actuating said piston, means of communication between said cylinder and said chamber, and means for [flowing a stream of air over and in heat-exchange relation with said walls.

2. A compressor unit comprising driving means having a rotatable output shaft, casing means forming a compressor body having the general shape of an annulus to provide a central air space that receives said shaft axially therein, said body including radially spaced inner and outer exterior peripheral walls forming a pulsation chamber that is isolated from and extends peripherally about said space, said body having a pocket opening radially therethrough, a fluid-compression assembly in said pocket and including a cylinder and head therefor carried by said body, a piston drivably connected to said shaft and reciprocable in the cylinder, means of communication between said cylinder and said chamber, and a fan spaced axially from said body and drivably connected to said shaft for moving air axially through said space.

3. The arrangement of claim 1 wherein said compressor body is comprised of mating generally hollow, openhaving an enclosed annular pulsation chamber bordered by generally concentric radially spaced outer and inner exterior wall portions, said inner wall portion circling and defining a central air space, one of said members having a pocket opening radially and endwise therethrough, a rotatable drive shaft extending axially in said space, a piston receivable in the pocket through the endwise opening region thereof drivably and reciprocably connected to; said shaft, a cylinder and head therefor receivable in said pocket through the radially opening region thereof and mounted on said one member in telescoping relation over said piston, and means Olf communication between said cylinder and said chamber.

5. In a compressor, in combination: casing means forming a compressor body having the general shape of an annulus to provide an unenclosed axial air space, said body including radially spaced apart inner and outer exterior peripheral walls defining a generally annular pulsation chamber that is isolated from and extends about the periphery of said space, said body having a pocket extending radially through adjacent portions of said inner and outer walls, a fluid-compression assembly in said pocket and including a cylinder and head therefor carried by said body, a piston reciprocable in the cylinder, and means in said space for actuating said piston, means of communication between said cylinder and said chamber, and means for flowing a stream of air over and in heat exchange relation with said walls.

6. The arrangement of claim 1 wherein said cylinder is a sleeve cylinder, said head is separate from and has interlocking connection with the outer end of the cylinder with the head being in metallic contact with both the cylinder and the compressor body, and 'wherein said means of communication includes inlet and exhaust valves mounted in the head with one of said valves communicating with said chamber.

7. A two-stage compressor comprising casing means forming a compressor body having the general shape of an annulus to provide an axial air space, said body including radially spaced inner and outer exterior peripheral walls defining a pulsation chamber that is isolated from and extends about the periphery of said space, said body having a pair of pockets opening radially therethrough, a low pressure fluid-compression assembly in one of said pockets in discharging communication with said pulsation chamber, a high pressure fluid-compression assembly in the other of said pockets and including a cylinder and head therefor carried by said body, a piston reciprocable in the cylinder and means in said space for actuating said piston, inlet and exhaust valves mounted in the head, means of communication between the inlet valve and the pulsation chamber, and means for flowing air over and in heat-exchange relation with said walls.

8. A two-stage compressor comprising casing means forming a compressor body having the general shape of an annulus to surround and define an unenclosed axial air space, said body including radially spaced apart inner and outer exterior peripheral walls defining a generally annular pulsation chamber that is isolated from communication with and extends about the periphery of said space, said body having a pair of pockets opening radially therethrough, a low pressure fluid-compression assembly in one of said pockets in discharging communication with said pulsation chamber, a high pressure fluid-compression assembly in the other of said pockets and including a cylinder and head therefor carried by said body, a piston reciprocable in the cylinder and means in said space for References Cited in the file of this patent UNITED STATES PATENTS Reavell July 23, 1907 8 Weiss Apr. 2, 1918 Halleck May 3, 1934 Miller Mar. 29, 1938 Willgoos Dec. 10, 1940 Wescombe Dec. 14, 1948 UNITED STATES PATENT OFFICE CERTIFICATE OF QORIRECTION Patent No 2,899,130 August ll, 195%? Robert E0 Sykes It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

Column 6, line 16, for "drivabl and reoiprocebly m and reciprooably drivably Signed and sealed this 23rd day of February 1960.,

SEAL) ttest:

KARL H. AXLINE ROBERT C. WATSUN Attesting Ofiicer Commissioner of Patents 

